Interpolation is the process of inserting new pixels between
existing pixels. The result is greater picture, and consequently, larger
file. Interpolation was invented for enlarging of images for printing and other
purposes. The interpolation was also used as good manipulation method for
confuse the purchaser by representing machine as better resolution source
as really is.

Interpolation works on creating estimated
values between existing pixels. Few methods are used for interpolating
algorithm: linear, bilinear, bicubic and fractal. As best is the bicubic method
considered. Still, some artifacts could be created, as ghosting, jaggies along
diagonals, and noise that can become emphasized.

Interpolation,
still, can't create details that are not captured with camera. It works better
when used on larger pictures in small doses. By interpolating small files to a
very large size, the picture can
be degradated more as is detailed. In other side, when picture is interpolated
to a smaller size, the noise and some other artifacts are reduced. Also, the
sharpening process has stronger affect to smaller images.